Magnetic head having short pole yoke length and method for fabrication thereof

ABSTRACT

The induction coil of the magnetic head of the present invention is fabricated in a patterned electrical insulation material, preferably utilizing reactive ion etch (RIE) techniques. The electrical insulation material is particularly patterned such that it is formed away from the ABS surface and in the location of the induction coil. A fill layer is deposited around the patterned electrical insulation material layer, such that the fill layer is disposed at the ABS surface. In a preferred embodiment, the patterned electrical insulation material is initially fabricated from hard baked photoresist and subsequent to the deposition of the fill layer the hard baked photoresist material is removed and replaced by SiO 2 . The SiO 2  is thereby located away from the ABS surface and the induction coil is subsequently fabricated within the SiO 2  material.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to magnetic heads forhard disk drives, and more particularly to magnetic heads having a finepitch induction coil and a shortened P2 magnetic pole yoke length, andmethods for the fabrication thereof.

[0003] 2. Description of the Prior Art

[0004] It is a goal of the hard disk drive industry to develop magneticheads that provide ever faster data writing speeds, such that increasedquantities of data can be written onto the hard disk in shorter periodsof time. Magnetic heads commonly include write heads having two magneticpole members, generally referred to as the P1 pole and the P2 pole(which typically includes a P2 pole tip and a yoke portion), and a flat,spiral induction coil that is fabricated between the P1 and P2 poles.Write head electrical current that passes through the induction coilcreates a magnetic flux in the two magnetic pole members, and themagnetic flux passes through the write head pole tip to create amagnetic field that writes magnetic data bits onto the media, such as ahard disk, that is disposed proximate the pole tip. To improve theperformance characteristics of hard disk drives, efforts have beendirected to increasing the speed with which data bits can be written bythe magnetic head onto the magnetic media.

[0005] One of the parameters that controls the rate at which data can bewritten is the rate with which magnetic flux changes can be made by thewrite head. This flux change rate is in part controlled by the magneticflux rise time of the write head, and the physical geometry of the writehead, particularly the P2 pole yoke length, is one of the significantparameters that determines the magnetic flux rise time. Therefore, ifthe magnetic flux rise time can be shortened, such as by shortening theyoke length, the data writing rate of a magnetic head can be increased.

[0006] Prior art efforts to shorten the yoke length have lead to thedevelopment of multiple layered induction coils. However, such multiplelayer induction coils, as are known in the prior art, are generallydifficult to reliably fabricate. Specifically, the prior art multiplelayer coil fabrication methods have generally employed well knownphotolithographic techniques which limit the definition of the inductioncoil line width. In addition, it is also difficult to remove the platingseed layer between the coil turns when the coil pitch is very small.Other methods that utilize image transfer techniques have resulted inproblems related to the difficulty of removing photoresist materialsand/or SiO₂ electrical insulation material from areas proximate the airbearing surface (ABS) of the magnetic head.

[0007] The present invention utilizes a reactive ion etching fabricationtechnique to achieve better physical characteristics for write head polecomponents including a shortening of the yoke length, whereby themagnetic flux rise time of the magnetic head is reduced, such that thedata writing rate of the magnetic head is increased.

SUMMARY OF THE INVENTION

[0008] The magnetic head of the present invention includes an inductioncoil having coil turns that are more accurately and reliably spaced dueto the use of reactive ion etching (RIE) fabrication techniques. In oneembodiment, following the fabrication of the first magnetic pole (P1)together with a P1 pole pedestal piece and a first back gap piece, anetch stop layer is deposited. Thereafter, a patterned layer of anetchable electrical insulation material, such as hard baked photoresistis fabricated in the induction coil location and particularly away fromthe ABS surface. This is followed by the deposition of an Al₂O₃ filllayer across the wafer surface and a CMP step. An induction coil is thenfabricated into the electrical insulation material and a patterned writegap layer is deposited. In this single coil embodiment, a flat P2 pole,including a P2 pole tip portion and a yoke portion, is then fabricatedon top of the write gap layer. The fabricated magnetic head will have afine pitch coil due to the use of RIE techniques, and the ABS surfacewill include the P1 pole, the P1 pole pedestal and the P2 pole tipsurrounded by the Al₂O₃ deposited material. No RIE etchable materialwill have been deposited at the ABS surface, and the subsequentpolishing of the ABS surface is thereby facilitated.

[0009] In a multilayer coil second preferred embodiment, a secondinduction coil layer is fabricated above the write gap layer inelectrical connection with the first induction coil layer. To accomplishthis, starting after the deposition of the write gap layer, a P2 poletip and second back gap piece are next fabricated. Thereafter, a secondpatterned layer of etchable electrical insulation material is fabricatedin the induction coil location, and particularly away from the ABSsurface (as was done with the first electrical insulation layer). Thisis followed by the deposition of an Al₂O₃ fill layer across the wafersurface and a further CMP step. A second induction coil is thenfabricated within the electrical insulation material, followed by apatterned insulation layer and the fabrication of the P2 pole yokepiece. No RIE etchable material will have been deposited at the ABSsurface, and the subsequent polishing of the ABS surface is therebyfacilitated. The RIE fabrication techniques of the present inventionthus facilitate the formation of fine pitched induction coils whichallow for a shortening of the yoke length of the P2 pole.

[0010] A further magnetic head embodiment has a single induction coillayer fabricated above the write gap layer, between a P2 pole tip and aback gap piece. The RIE fabrication techniques described herein areemployed to create it.

[0011] In an improved further magnetic head embodiment of the presentinvention, the induction coil (or multiple coil layers, depending uponthe particular embodiment) is fabricated within an SiO₂ electricalinsulation layer. In fabricating such a head, the patterned hard bakedphotoresist electrical insulation layer is removed following thedeposition of the Al₂O₃ fill layer. Following the removal of the hardbaked resist electrical insulation layer, SiO₂ is deposited upon thewafer surface to fill the location previously occupied by the removedhard baked photoresist. Thereafter, the induction coil is fabricatedinto the SiO₂ layer. As with the hard baked photoresist embodiments, theRIE etchable SiO₂ electrical insulation layer is particularly fabricatedaway from the ABS surface, such that subsequent polishing of the ABSsurface is facilitated. The SiO₂ electrical insulation possessespreferred thermal conductivity as compared to the hard bakedphotoresist, and thereby provides improved performance characteristicsto the fine pitch induction coil magnetic heads of this embodiment ofthe present invention.

[0012] It is an advantage of the magnetic head of the present inventionthat the yoke length of the second magnetic pole of the write headelement is reduced.

[0013] It is another advantage of the magnetic head of the presentinvention that the RIE etchable material in which the induction coil isfabricated is not deposited at the ABS surface of the magnetic head.

[0014] It is a further advantage of the magnetic head of the presentinvention that the magnetic flux rise time of the write head element isshortened.

[0015] It is yet another advantage of the magnetic head of the presentinvention that an increase in the data writing rate is achieved.

[0016] It is an advantage of the disk drive of the present inventionthat it includes a magnetic head wherein the yoke length of the secondmagnetic pole of the write head element is reduced.

[0017] It is another advantage of the hard disk drive of the presentinvention that it includes a magnetic head in which the RIE etchablematerial in which the induction coil is fabricated is not deposited atthe ABS surface of the magnetic head.

[0018] It is a further advantage of the hard disk drive of the presentinvention that it includes a magnetic head in which the magnetic fluxrise time of the write head element is shortened.

[0019] It is yet another advantage of the hard disk drive of the presentinvention that it includes a magnetic head in which an increase in thedata writing rate is achieved.

[0020] It is an advantage of the method for fabricating a magnetic headof the present invention that the RIE etchable material in which theinduction coil is fabricated is not deposited at the ABS surface of themagnetic head.

[0021] The foregoing and other objects, features, and advantages of thepresent invention will be apparent from the following detaileddescription of the preferred embodiment which makes reference to theseveral figures of the drawing.

IN THE DRAWINGS

[0022]FIG. 1 is a simplified depiction of a hard disk drive of thepresent invention;

[0023]FIG. 2 is a top plan view depicting a typical prior art magnetichead and providing a view orientation that is utilized in the followingfigures and in describing the present invention;

[0024]FIG. 3 is a side cross-sectional view taken along lines 3-3 ofFIG. 2 of an initial fabrication step of the magnetic head of thepresent invention, which serves as a starting point for the detaileddescription thereof;

[0025]FIG. 4 is a side cross-sectional view of an initial fabricationstep of the magnetic head of the present invention, which serves as astarting point for the detailed description thereof;

[0026] FIGS. 5-14 are views depicting further fabrication steps of afirst embodiment of the present invention;

[0027] FIGS. 15-27 are views depicting fabrication steps of a secondembodiment of the present invention;

[0028]FIG. 28 is a side cross-sectional view depicting anotherembodiment of the present invention;

[0029] FIGS. 29-38 are views depicting a further embodiment of thepresent invention;

[0030]FIG. 39 is a cross-sectional view depicting yet another embodimentof the present invention; and

[0031]FIG. 40 is a side cross-sectional view depicting yet a furtherembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032]FIG. 1 is a top plan view that depicts significant components of ahard disk drive which includes the magnetic head of the presentinvention. The hard disk drive 10 includes a magnetic media hard disk 12that is rotatably mounted upon a motorized spindle 14. An actuator arm16 is pivotally mounted within the hard disk drive 10 with a magnetichead 100 of the present invention disposed upon a distal end 22 of theactuator arm 16. A typical hard disk drive 10 may include a plurality ofdisks 12 that are rotatably mounted upon the spindle 14 and a pluralityof actuator arms 16 having a magnetic head 100 mounted upon the distalend 22 of the actuator arms. As is well known to those skilled in theart, when the hard disk drive 10 is operated, the hard disk 12 rotatesupon the spindle 14 and the magnetic head 100 acts as an air bearingslider that is adapted for flying above the surface of the rotatingdisk. The slider includes a substrate base upon which the various layersand structures that form the magnetic head are fabricated. Such headsare fabricated in large quantities upon a wafer substrate andsubsequently sliced into discrete magnetic heads 100.

[0033]FIG. 2 is a top plan view of a typical prior art magnetic head 23,and FIG. 3 is a side cross-sectional view taken along lines 3-3 of FIG.2. Referring to FIGS. 2 and 3, the prior art magnetic head 23 includes aread head magnetic shield (S1) layer 24 that is fabricated upon theupper surface 26 of a wafer substrate 27, a read head element 28 that isfabricated between insulation layers 32 and 34 upon the S1 shield 24,and a second magnetic shield (S2) layer 36 that is fabricated upon theupper insulation layer 34. A further insulation layer 40 is depositedupon the S2 shield 36 and a first magnetic pole (P1) layer 50 is nextfabricated upon the insulation layer 40. As is also well known to thoseskilled in the art, in a type of magnetic head termed a merged head, theP1 pole layer 50 and the S2 shield layer 36 are merged into a singlelayer that performs the functions of the S2 shield 36 when the head isreading data from a hard disk, and performs the function of the P1magnetic pole layer when the magnetic head is writing data to a harddisk. The insulative layer 40 is not present in such a merged head. Thepresent invention, as is discussed below in detail, may be fabricated asa standard magnetic head or as a merged magnetic head, (although it isdepicted herein as a standard magnetic head) as will be clear to thoseskilled in the art upon reading further.

[0034] The typical prior art magnetic head 23 depicted in FIGS. 2 and 3further includes a patterned write gap layer 52 that is fabricated uponthe P1 pole 50. Thereafter, a spiral, planar induction coil 56 isfabricated such that inner portions of a plurality of induction coilturns 60 formed with insulation 62 between them, are disposed above theP1 pole 50. Outer portions 64 of the induction coil turns complete thespiral induction coil 56. Typically, a first induction coil electricalinterconnect 70 is formed in the central portion of the induction coilspiral, and a second electrical interconnect 74 is formed at the outeredge of the induction coil 56. Following the fabrication of theinduction coil 56, a second magnetic pole (P2) 80 is fabricated abovethe induction coil 56. The second magnetic pole 80 includes a secondmagnetic pole tip 84 and a yoke portion 88, and the inner portions 60 ofthe induction coil traces pass between the P1 pole 50 and the P2 poleyoke 88. The yoke 88 is magnetically connected with the first pole 50through a back gap piece 90. The magnetic head is later fabricated toinclude a polished air bearing surface (ABS) 92, as is well known bythose skilled in the art.

[0035] When the write head current is fed through the electricalinterconnects 70 and 74, and thus through the spiral coil 56, a magneticflux is created within the two magnetic pole members 50 and 80 such thatthe magnetic flux passes across the write gap layer 52 between the P1pole 50 and the P2 pole tip 84. The passage of the magnetic flux acrossthe write gap creates a magnetic field that influences the magneticmedia hard disk 12 that is disposed proximate the write gap in a harddisk drive 10, such that magnetic data bits are written onto the harddisk 12. The rate of change of the magnetic flux affects the datawriting rate of the magnetic head, and the magnetic flux change rate isin turn affected by the magnetic flux rise time of the magnetic poles.Where the magnetic flux rise time is decreased the data writing rate isgenerally increased. These structures and features are well known tothose skilled in the art and a further detailed description of them isnot deemed necessary.

[0036] One of the physical parameters that controls the magnetic fluxrise time is the length of the yoke 88 between the pole tip 84 and theback gap piece 90. Basically, where the length of the yoke is reduced,the magnetic flux flow path is reduced, and the magnetic flux rise timeis thereby decreased. However, the yoke length cannot arbitrarily beshortened because several induction coil turns 60 must pass beneath theyoke 88 in order to provide the electromagnetic energy to the yoke thatinduces the magnetic flux within it. Therefore, a limiting factor inshortening the length of the yoke 88 is that several induction coils 60must fit under the yoke, and the width of the coil turns, together withthe insulation space 62 required between the coil turns thereby controlsthe length of the yoke 88.

[0037] Efforts have been undertaken in the prior art to increase themagnetic flux that is created in the two magnetic poles by increasingthe number of induction coil turns that are fabricated between the twomagnetic poles 50 and 88. Such efforts have included the fabrication ofmultiple layered induction coils, and the present invention includes butis not limited to a method for fabricating a multiple layer inductioncoil. Of course, where the same number of induction coil turns arefabricated in a multiple layer induction coil, as opposed to a singlelayer induction coil, the yoke length is reduced. The magnetic head 100of the present invention includes improved coil fabrication techniquessuch that the magnetic head of the present invention has a finer pitch(coil turn to coil turn distance), and a shortened yoke length isthereby achieved. As a result, the magnetic head of the presentinvention has a decreased magnetic flux rise time and therefore achievesa faster data writing rate.

[0038]FIG. 4 provides a starting point in the description of themagnetic head embodiments of the present invention, and identicalstructures are numbered identically in subsequent figures of thisdisclosure. As depicted therein, a magnetic head embodiment 100 includesa first read head shield 24 that is disposed upon a surface 26 of aslider body 27. A read head element 28 is formed between insulationlayers 32 and 34 and a second read head shield 36 is formed upon theinsulation layer 34. An insulation layer 40 is fabricated above thesecond read head shield 36, and the P1 pole layer 50 is then fabricatedupon the insulation layer 40. As described above, this basic structureof FIG. 4 is well known, and a detailed description of its variousstructural details is not necessary to an understanding of the presentinvention. That is, the present invention can be utilized with variousread head element structures including the merged magnetic headstructure described hereinabove.

[0039] The next step in the fabrication of a first preferred embodiment100 of a magnetic head 20 of the present invention is the creation of astepped P1 pole 110 as is depicted in FIG. 4. The stepped P1 pole iscreated by fabricating an additional raised P1 pole segment or pedestal110 in magnetic connection with the P1 pole layer 50 proximate the ABSsurface 92 of the magnetic head 100. The pedestal 110 is generallyfabricated centrally above the read head element 28. Additionally, a P1pole back gap piece 114 is also fabricated in magnetic connection withthe P1 pole layer 50. The P1 pole pedestal 110 and back gap piece 114may be fabricated utilizing a patterned photoresist and well knownphotolithographic techniques to plate the pedestal 110 and back gappiece 114 onto the P1 layer 50. Where photolithographic techniques areutilized, the pedestal 110 and back gap piece 114 may be fabricated fromthe same material as the P1 layer, such as Permalloy, or they may bepreferably fabricated from another magnetic material, such as, but notlimited to, NiFe 45/55 which has higher magnetic moment properties thanPermalloy, and thus provides different performance characteristics to amagnetic head 100 that is fabricated using it. The thickness of thepedestal 110 and the back gap piece 114 will generally determine thethickness of induction coil members that are subsequently fabricatedwithin the magnetic head 100, as are described herebelow.

[0040] As depicted in FIG. 5, a thin film layer 116 is next depositedacross the wafer surface and upon the device depicted in FIG. 4. Thethin film layer 116 is composed of a material, such as alumina, thatwill act as an electrical insulation layer and as an etch stop materialin a subsequent reactive ion etch (RIE) etching process that isdescribed herebelow. Thereafter, as depicted in FIG. 6, a patternedelectrical insulation layer 120 of hard baked photoresist is fabricated.As is best seen in the top view presented in FIG. 9 (and describedherebelow), the patterned hard baked photoresist 120 is shaped to coverthe area in which the spiral induction coil is to be fabricated, and thespiral induction coil trenches are subsequently fabricated into the hardbake photoresist 120. It is significant to note that the pattern of thehard baked resist 120 is specifically formed away from the ABS surface92 that will subsequently be created in the fabrication of the magnetichead 100. This feature is particularly helpful in fabricating themagnetic head 100 of the present invention, in that it has provendifficult to effectively polish the ABS surface where RIE etchablematerial is located at the ABS surface.

[0041] Exemplary materials of the photoresist layer 120 includespolymeric materials such as hard baked novolac or F-containing low kpolymer, or similar photoresist insulation materials that can be hardbaked yet readily etched in the RIE process that is to be conductedlater. The thickness of the layer 120 is generally at least as thick asthe P1 pedestal 110 which will correspond to the desired thickness of afirst layer of induction coil traces that will be fabricated within thelayer 120, as is described hereinbelow. As is depicted in FIG. 7, alayer of alumina fill 122 is next deposited across the surface of thewafer, preferably to a depth that exceeds the thickness of the P1pedestal 110 and the back gap piece 114. As is next depicted in FIGS. 8and 9, wherein FIG. 9 is a top plan view of FIG. 8, a CMP step is nextconducted to remove excess alumina 122 and portions of the hard bakedresist layer 120, and the portion of the etch stop layer 116 depositedon top of the P1 pedestal 110 and back gap 114, such that a flat surface124 is formed and the upper surfaces 126 and 128 of the P1 pedestal 110and back gap 114 respectively are exposed. Thereafter, as depicted inFIG. 10, a thin etching mask layer 130 is fabricated upon the flat uppersurface 124 of the layer 120, and a thin photoresist layer 131 is thendeposited upon the layer 130. A photolithographic step is next conductedin which induction coil pattern openings 132 are formed in thephotoresist layer 131. Then a first RIE step is conducted with anappropriate etching species that forms corresponding coil patternopenings 134 in the mask layer 130 for fabricating induction coiltrenches into the layer 120. It is advantageous that the RIE mask can befabricated with a thickness of only approximately 0.5 microns, such thata fine pitch induction coil can more easily be fabricated.

[0042] As depicted in FIG. 11, utilizing an ion etch process which ispreferably an RIE process, induction coil trenches 138 are etchedthrough the openings 134 in the mask 130 and downward through the layer120 to the etch stop layer 116. Therefore, the relationship of thematerials which comprise the RIE mask 130, the etch stop layer 116 andthe hard baked photoresist layer 120 must be such that during the RIEstep the material comprising the layer 120 is relatively easily etched,while the material comprising the RIE mask 130 and the etch stop layer116 is significantly more slowly etched. By way of example, where theetchable insulation material layer 120 is composed of an organic polymersuch as a hard baked resist, a reactive ion etch process utilizing a gassuch as oxygen can be utilized, and the RIE mask 130 may be formed ofmaterials such as TaO and SiO₂, and the etch stop layer 116 may consistof an electrical insulation material such as Al₂O₃.

[0043] Thereafter, as depicted in FIG. 12, an induction coil structureis fabricated in the typical manner. That is, a seed layer 142, whichmay consist of sublayers of Ta, NiFe or Cr, followed by copper issputter deposited onto the wafer to form a good electricalinterconnection and physical bonding at the bottom of the trenches 138.The induction coil traces 144 which are typically composed of copper,are next fabricated in an electroplating process to fill the inductioncoil trenches 138 with copper 145. Alternatively, a chemical vapordeposition process may be used to deposit the copper. Thereafter, asdepicted in FIG. 13, a chemical mechanical polishing step (CMP) isconducted to remove the excess copper 145 and the RIE mask 130, suchthat a flat upper surface 146 is formed. It is preferable that the CMPpolishing step be conducted to expose the upper surface 126 of the P1pole piece, and the upper surface 128 of the back gap piece 114, suchthat good magnetic flux flow through the magnetic poles of the magnetichead will be achieved. It can now be seen that a first induction coillayer structure 150 has been fabricated within the etchable insulationmaterial layer 120. Due to the excellent process control parameters thatare achievable by utilizing the reactive ion etch process describedabove, the induction coil traces 144 can be accurately fabricated withminimal spacing of insulative layer material 120 therebetween.Additionally, due to the use of the RIE process in fabricating the coiltrenches 138 within the etchable insulation layer 120, the difficulty inremoving the induction coil seed layer between coil lines, as is foundin the prior art, is eliminated.

[0044] As is depicted in FIG. 14, a completed magnetic head 100 may nextbe fabricated by depositing a patterned write gap layer 154 upon theupper surface 146, such that an opening 158 is formed above the surface128 of the back gap piece 114. Thereafter, a flat P2 pole 162, includinga P2 pole tip portion 166 and a yoke portion 170 may be fabricated ontop of the write gap layer 154 utilizing standard photolithographictechniques as are well known to those skilled in the art, such that theyoke portion 170 is deposited upon the upper surface 128 of the back gappiece 114. After conducting further fabrication steps, includingencapsulation 174, as are well known to those skilled in the art, amagnetic head 100 of the present invention is completed.

[0045] A significant feature of the magnetic head 100 is that it isformed with a fine pitch induction coil that was fabricated utilizingRIE techniques, including a particularly patterned hard bakedphotoresist insulation layer 120 that was patterned such that it wasfabricated away from the ABS surface 92 of the head (see FIG. 9).

[0046] A second preferred embodiment 180 of a magnetic head of thepresent invention having a multiple layer coil can now be described withthe aid of FIGS. 15-27. Basically, having fabricated a first inductioncoil layer structure 150, a second induction coil layer can subsequentlybe fabricated upon the flat surface of the write gap layer 154, byessentially repeating the coil fabrication process described above.Particularly, as depicted in FIGS. 15, a patterned write gap layer 154has been deposited upon the flat surface 146. The patterning of thewrite gap layer 154 provides an opening 158 to expose the upper surface128 of the back gap piece 114, and an opening 188 to expose the uppersurface 192 of a central induction coil trace pad 196 for a subsequentelectrical connection thereto, as is well known to those skilled in theart. A magnetic P2 pole tip piece 204 is next formed upon the write gaplayer 154, and a second back piece 208 is formed upon the surface 128 ofthe first back piece 114. Standard photolithographic process steps areutilized to fabricate the P2 pole tip 204 and the back piece 208, and adetailed description of the process steps is not necessary as they arewell known to those skilled in the art. Basically, the steps include thedeposition of a seed layer, followed by a photoresist layer that issubsequently patterned and the electroplating of the P2 pole tip 204 andback piece 208 into the patterned photoresist layer, followed by theremoval of the photoresist layer and seed layer. The P2 pole tip 204 isgenerally centrally disposed relative to the P1 pedestal 110 and inalignment with the read head element 28.

[0047] As is depicted in FIG. 16, a patterned second etch stop layer 212may next be fabricated upon the wafer surface; where the write gap layer154 is particularly thin, the etch stop layer 212 insures that etchingthrough the write gap layer will not occur during the subsequent RIEetching step described below. The patterning of the second etch stoplayer 212 includes a formation of openings 216 for connection to theelectrical interconnects 196 fabricated in the first coil layer 150.Thereafter, as depicted in FIGS. 17 and 18, a patterned second etchableinsulation material layer 220 is fabricated upon the etch stop layer212; the layer 220 is preferably composed of a hard baked photoresist.The thickness of the layer 220 is generally thicker than the thicknessof the P2 pole piece 204 which determines the thickness of the secondinduction coil trenches that will be fabricated therein, as is describedbelow. As is best seen in the top view presented in FIG. 20 anddescribed herebelow, the patterned hard baked photoresist 220 is shapedto cover the area in which the upper layer of the spiral induction coilis to be fabricated, and it is significant to note that the pattern ofthe hard baked resist 220 is specifically formed away from the ABSsurface 92 that will subsequently be created in the fabrication of themagnetic head 180. The fabrication of the patterned hard bakedphotoresist insulation layer 220 is therefore similar to the photoresistlayer 120 described hereabove. Exemplary materials of the layer 220include the materials that were utilized in forming the first insulationlayer 120, including polymeric materials such as hard baked novolac orF-containing low k polymer. Preferably the layers 220 and 120 arecomposed of the same material. As is next depicted in FIG. 18, analumina fill layer 228 is next deposited across the surface of thewafer, preferably to a depth that exceeds the thickness of the P2 poletip 204. Thereafter, as depicted in FIGS. 19 and 20, in which FIG. 20 isa top plan view of FIG. 19, a CMP step is conducted to remove excessalumina 228 and portions of the hard bake resist 220, and the portionsof the second etch stop layer 212 that are deposited on top of the P2pole tip 204 and the back gap 208, such that a flat surface 240 isformed and the upper surfaces 244 and 248 of the P2 pole tip 204 andback gap 208 respectively are exposed. The alumina fill 228 is locatedat the ABS surface 92, whereby the polishing of the ABS surface isfacilitated.

[0048] As depicted in FIG. 21, a patterned second induction coil etchingmask 260 is next fabricated upon the top surface 240 of the layer 220.The pattered mask 260 includes openings 264 for the fabrication of asecond layer of induction coil trenches, and an opening 268 for anelectrical interconnect. The electrical interconnect opening 268 istherefore fabricated in alignment with the patterned opening 216 in theetch stop layer 212 and the electrical interconnects 196 of the firstcoil layer 150.

[0049] As is next depicted in FIG. 22, utilizing an ion etch processwhich is preferably a reactive ion etch (RIE) process, induction coiltrenches 280 and an interconnect trench 284 are etched through the layer220. The etching of the induction coil trenches 280 is halted by theetch stop layer 212, whereas the etching of the interconnect trench 284continues until the electrical interconnect 196 of the first coil layer150 is reached. Therefore, the relationship of the materials whichcomprise the RIE mask 260 and the second etch stop layer 212 and thesecond etchable insulation layer 220 must be such that during the RIEstep, the material comprising the layer 220 is relatively easily etched,while the material comprising the RIE mask 260 and the etch stop layer212 is significantly more slowly etched. As described hereabove, wherethe second etchable insulation material layer 220 is composed of anorganic polymer such as a hard baked resist, a reactive ion etch processutilizing a gas such as oxygen can be utilized, and the RIE mask mayconsist of TaO or siO2 and etch stop layer 212 may preferably consist ofAl₂O₃.

[0050] Thereafter, as depicted in FIG. 23, a seed layer 292 is nextdeposited onto the substrate and into the coil trenches 280. As is knownin the art, a typical seed layer 292 is preferably a sputter depositeddual layer composed of a tantalum initial sublayer part and a coppersubsequent sublayer part. An upper induction coil structure is thenfabricated by electroplating induction coil material 296, such as copperinto the coil trenches 280 in an electrodeposition process, as is wellknown to those skilled in the art. The copper filling can also beachieved by chemical vapor deposition methods. Thereafter, as depictedin FIG. 24, a CMP process step is conducted to remove the excess copperand the RIE mask 260, such that a flat upper surface 302 is formed. Itis significant to note that the upper surface 308 of the back gap piece208 and the upper surface 312 of the P2 pole tip 204 are exposed in thisCMP process.

[0051] Next, as depicted in FIG. 25, a patterned insulative layer 316 isfabricated upon the upper surface 302 of the coil pattern with anopening 320 formed therein to provide for magnetic connection of a yokemember to the surface 308 of the back gap piece 208. Thereafter, asdepicted in FIG. 26, using well known photolithographic techniques, theyoke portion 328 of the second magnetic pole layer is then fabricatedonto the device to magnetically connect the P2 pole tip 204 with theback piece 208. A gap or recess 332 is preferably formed between theyoke 328 and the air bearing surface 92 that will ultimately be formed,as is well understood by those skilled in the art. Finally, furtherfabrication steps as are known in the art are then utilized to producethe electrical lead connections and, as depicted in FIG. 27, themagnetic head is then encapsulated 336, and further well known steps aretaken, including slicing the wafer and heads for polishing the heads atthe ABS surface 92, to form the completed magnetic head 180.

[0052] An alternative preferred embodiment 350 of the present inventioncan now be described based on an understanding of magnetic heads 100 and180. Specifically, as described above, magnetic head 100 is formed witha single layer induction coil that is fabricated beneath the write gaplayer 154 and between the P1 pole pedestal 110 and the back gap 114, andthe magnetic head embodiment 180 includes a multiple layer coil whereina first coil layer is fabricated below the write gap layer, and a secondcoil layer is fabricated above the write gap layer 154 between a P2 poletip 204 and a back gap piece 208. The alternative magnetic headpreferred embodiment 350, as depicted in FIG. 28, includes a singlelayer induction coil 354 that is fabricated above the write gap layer154, between the P2 pole tip 204 and the back gap piece 208. A detaileddescription of the fabrication of this alternative embodiment 350 issubstantially identical to the fabrication steps of the second layer ofthe multiple layer coil embodiment 180, and a further descriptionthereof is not deemed necessary, in that one skilled in the art willwell understand how to fabricate it in light of the preceding detaileddescription of the induction coil fabrication steps described hereabove.It is significant however to note that the hard baked resist 220 inwhich the induction coil 354 is fabricated, would also be patterned awayfrom the ABS surface 92, such that no new material will be exposed onthe ABS surface, which may affect the interaction between the head andthe disk.

[0053] In a typical embodiment, the P1 pole pedestal 110 and P2 pole tip204 have thicknesses of approximately 2 microns, such that the thicknessof the coil turns 144 and 280 is approximately 2 microns. The width ofthe coil turns can be from approximately 0.75 microns to as narrow asapproximately 0.25 microns, and an insulation width between the coilturns of approximately 0.15 to 0.25 microns is sufficient to separatethe coil turns, such that the coil pitch of the present invention isfrom approximately 0.4 microns to approximately 1.0 microns. The aspectratio (thickness/width) of the coil turns is from approximately 2.6 toapproximately 8.

[0054] As can now be understood, each of the coil turns has a relativelynarrow width and a relatively large thickness, such that each of thecoil turns has a relatively high aspect ratio, and the pitch (or coilturn to coil turn distance) is thereby reduced. As indicated above, thereduction in the coil pitch means that the same number of coil turnswill fit in a shorter space, such that the length of the yoke betweenthe pole tip and the back gap piece is shortened, and the shortened yokeleads to a faster magnetic flux rise time, such that a higher datawriting rate is obtained.

[0055] A further magnetic head embodiment 400 of the present inventionis depicted in FIGS. 29 through 38 as are next described. Commencingwith FIG. 29, a side cross-sectional view of a fabrication step of themagnetic head 400 is presented; the fabrication stage of the magnetichead 400 can be readily understood with reference to FIG. 8, describedin detail hereabove, and wherein common structures are identified withidentical numerals. Briefly, a P1 pole pedestal 110 and a back gap piece114 are fabricated upon a P1 pole piece 50. Thereafter, an etch stoplayer 116 has been deposited, followed by the fabrication of a patternedhard baked resist layer 120. An alumina fill layer 122 has beendeposited, followed by a CMP step, such that the hard baked resist islocated away from the ABS surface 92 and solely in the area where theinduction coil is to be fabricated.

[0056] As depicted in FIGS. 30 and 31, wherein FIG. 30 is across-sectional view and FIG. 31 is a top plan view of FIG. 30, thefabrication of the magnetic head 400 proceeds from this point, with thestep of removal of the hard baked resist 120 from the wafer, leaving agenerally doughnut shaped cavity 408 in the locations in which aninduction coil is to be fabricated. The back gap piece 114 is located inthe center of the doughnut shaped cavity 408, and an oxygen RIE processis preferably (though not necessarily) utilized to remove the hard bakedresist 120. Thereafter, as depicted in FIG. 32, a layer 412 of SiO₂ isdeposited across the surface of the wafer in a depth sufficient to fillthe cavity 408. As is next depicted in FIG. 33, a CMP process step isthen performed to remove the excess SiO₂ from the surface of the wafer,such that the remaining SiO₂ layer 412 fills the cavity 408 previouslyfilled by the hard baked resist 120. It is significant to understandthat the SiO₂ material 412 is now located only in the doughnut shapedcavity 408, and is thus disposed away from the ABS surface location 92of the magnetic head 400, just as the hard baked material 120 waslocated away from the ABS surface 92 in embodiments 100, 180 and 350, ashas been discussed hereabove. This feature is significant because it hasproven difficult to effectively polish the ABS surface 92 when SiO₂material is located at the ABS surface, due to the relative hardness ofSiO₂. Thus, by first fabricating the hard baked photoresist 120 in theinduction coil location only, and then removing it and replacing it withSiO₂ material 412 that is similarly resident only in the induction coilarea, the induction coil can now be fabricated in an SiO₂ layer 412where the Si0 ₂ is formed away from the ABS surface 92.

[0057] A next step in fabricating the magnetic head 400 is thefabrication of a patterned RIE mask 130 upon the SiO₂ insulation layer412, as is depicted in FIG. 34, followed by openings 134 being formed inthe RIE mask 130 at locations where induction coil trenches are desired.The RIE mask 130 can be fabricated using photoresist and the openings134 found in a photolithographic process, when the photoresist isresistant to a fluorine species RIE process next described. Thereafter,as depicted in FIG. 35, an RIE etching step is conducted wherein theSiO₂ material 412 is effectively etched to create induction coiltrenches 138, while the mask 130 and etch stop layer material 116 arenot significantly etched. The etch stop layer 116 is preferably composedof Al₂O₃, and a fluorine containing gas such as CF₄ is utilized in theRIE process, because SiO₂ is substantially more easily etched byfluorine containing species than Al₂O₃.

[0058] As is next depicted in FIG. 36, and as has been describedhereabove, a copper induction coil is preferably fabricated into theinduction coil trench by first depositing a seed layer 142, followed bythe electroplating of copper 145 to fill the trenches 138. Thereafter,as depicted in FIG. 37, a CMP step is performed to yield a flat uppersurface 146, wherein the upper surface 128 of the back gap piece 114 isexposed. As is depicted in FIG. 38, and described hereabove, a singlelayer induction coil magnetic head may be completed by the deposition ofa write gap layer 154, followed by the fabrication of a P2 pole 162,including a pole tip portion 166 and a yoke portion 170, followed byfurther processing steps to ultimately complete the encapsulation 174 ofthe magnetic head, followed by the slicing of the wafer, fabrication ofthe ABS surface 92 and ultimately the complete fabrication of discretemagnetic heads. These various steps are well known to those skilled inthe art.

[0059] Alternatively, as depicted in FIG. 39, a magnetic head 420 may befabricated having a multiple layer induction coil, similar to thatdepicted in FIG. 27, but in which the hard baked resist 120 and 220 inboth induction coil layers has been etched away and replaced with SiO₂material 412 and 424 respectively, according to the process stepsdescribed above with reference to FIGS. 30-33 of the magnetic head 400.

[0060] Alternatively, as depicted in FIG. 40, a further magnetic head440 may be fabricated having a single layer induction coil, similar tothat depicted in FIG. 28, but in which the hard baked resist 220 in theinduction coil layer has been etched away and replaced with SiO₂material 444, according to the process steps described above withreference to FIG. 28 of the magnetic head 350.

[0061] A significant advantage of the magnetic heads, such as magnetichead 400, 420 and 440 in which the hard baked resist has been replacedby SiO₂, is that SiO₂ is a significantly better heat conductor than hardbaked resist and has substantially less thermal expansion capacity.Thus, magnetic heads having an induction coil fabricated within SiO₂will have less of a heat buildup problem than induction coils fabricatedwithin hard baked resist. Heat buildup within a magnetic head can createperformance problems, as is well known to those skilled in the art,particularly as the fine pitch coil dimensions decrease along with thesize of other components of the magnetic head. The superior heatconducting properties of SiO₂ will therefore contribute to superiorperformance of the magnetic heads of the present invention as componentdimensions are decreased.

[0062] While the present invention has been shown and described withregard to certain preferred embodiments, it is to be understood thatthose skilled in the art will no doubt devise certain alterations andmodifications in form and detail hereof that nevertheless include thetrue spirit and scope of the invention. It is therefore intended thatthe following claims cover all such alterations and modifications hereofwhich nevertheless include the true spirit and scope of the invention.

What is claimed is:
 1. A magnetic head, comprising: a substrate base; awrite head being fabricated above said substrate base, including: atleast two magnetic poles; an electrical insulation layer being disposedbetween said magnetic poles such that no portion of said electricalinsulation layer is disposed at an air bearing surface (ABS) of themagnetic head; a fill layer being disposed around said electricalinsulation layer such that portions of said fill layer are disposed atsaid ABS surface; an induction coil being disposed within saidelectrical insulation layer.
 2. A magnetic head as described in claim 1wherein said electrical insulation layer is composed of a substanceselected from the group consisting of hard baked resist and SiO₂.
 3. Amagnetic head as described in claim 2 wherein said induction coil is asingle layer induction coil.
 4. A magnetic head as described in claim 2wherein said induction coil is a multiple layer induction coil, andwherein each layer of said multiple layer coil is disposed within aseparate electrical insulation layer, and each said electricalinsulation layer is disposed within a separate fill layer, and whereinno portion of either said electrical insulation layers is disposed atsaid ABS surface, and wherein portions of each said fill layer aredisposed at said ABS surface.
 5. A magnetic head as described in claim 1wherein said fill layer is comprised of Al₂O₃.
 6. A magnetic head asdescribed in claim 5 wherein said etch stop layer is comprised of Al₂O₃.7. A magnetic head, comprising: a substrate base; a first magnetic pole(P1) being disposed above said substrate base; a P1 pole pedestal beingdisposed upon said P1 pole; an etch stop layer being disposed upon saidP1 pole; an electrical insulation layer being disposed upon said etchstop layer, said electrical insulation layer being patterned such thatno portion of said electrical insulation layer is disposed at an airbearing surface (ABS) of the magnetic head; a fill layer being disposedaround said electrical insulation layer such that portions of said filllayer are disposed at said ABS surface; an induction coil being disposedwithin said electrical insulation layer; a write gap layer beingdisposed above said fill layer; a second magnetic pole (P2) beingdisposed upon said write gap layer.
 8. A magnetic head as described inclaim 7 wherein said electrical insulation layer is comprised of amaterial selected from the group consisting of an organic polymer andSiO₂.
 9. A magnetic head as described in claim 8 wherein said fill layeris comprised of Al₂O₃.
 10. A magnetic head as described in claim 9wherein said etch stop layer is comprised of Al₂O₃.
 11. A magnetic head,comprising: a substrate base; a first magnetic pole (P1) being disposedabove said substrate base; a write gap layer being disposed above saidP1 pole; a P2 pole tip being disposed above said write gap layer; anelectrical insulation layer being disposed above said write gap layer,said electrical insulation layer being patterned such that no portion ofsaid electrical insulation layer is disposed at an air bearing surface(ABS) of the magnetic head; a fill layer being disposed around saidelectrical insulation layer such that portions of said fill layer aredisposed at said ABS surface; an induction coil being disposed withinsaid electrical insulation layer; a second electrical insulation layerbeing disposed above said induction coil; a P2 pole yoke being disposedabove said second electrical insulation layer.
 12. A magnetic head asdescribed in claim 11, wherein said electrical insulation layer iscomposed of a substance selected from the group consisting of an organicpolymer and SiO₂.
 13. A magnetic head as described in claim 12, whereinan etch stop layer is disposed on portions of said write gap layer, andsaid electrical insulation layer is disposed upon said etch stop layer.14. A magnetic head as described in claim 13 wherein said fill layer iscomprised of Al₂O₃.
 15. A magnetic head as described in claim 14 whereinsaid etch stop layer is comprised of Al₂O₃.
 16. A magnetic head,comprising: a substrate base; a first magnetic pole (P1) being disposedabove said substrate base; a P1 pole pedestal being disposed upon saidP1 pole; a first etch stop layer being disposed upon said P1 pole; afirst electrical insulation layer being disposed upon said etch stoplayer, said first electrical insulation layer being patterned such thatno portion of said first electrical insulation layer is disposed at anair bearing surface (ABS) of the magnetic head; a first fill layer beingdisposed around said first electrical insulation layer such thatportions of said first fill layer are disposed at said ABS surface; afirst induction coil layer being disposed within said first electricalinsulation layer; a write gap layer being disposed above said first filllayer; a P2 pole tip being disposed above said write gap layer; a secondelectrical insulation layer being disposed above said write gap layer,said second electrical insulation layer being patterned such that noportion of said second electrical insulation layer is disposed at saidABS surface of the magnetic head; a second fill layer being disposedaround said second electrical insulation layer such that portions ofsaid second fill layer are disposed at said ABS surface; a secondinduction coil layer being disposed within said second electricalinsulation layer; a third electrical insulation layer being disposedabove said second induction coil layer; a P2 pole yoke being disposedabove said third electrical insulation layer.
 17. A magnetic head asdescribed in claim 16, wherein said first and second electricalinsulation layers are composed of a substance selected from the groupconsisting of an organic polymer and SiO₂.
 18. A magnetic head asdescribed in claim 16, wherein a second etch stop layer is disposed onportions of said write gap layer, and said second electrical insulationlayer is disposed upon said second etch stop layer.
 19. A magnetic headas described in claim 18 wherein each said fill layer is comprised ofAl₂O₃.
 20. A magnetic head as described in claim 19 wherein each saidetch stop layer is comprised of Al₂O₃.
 21. A hard disk drive comprising:a motor for rotating a spindle; a magnetic medium disk mounted on saidspindle; an actuator assembly including a magnetic head for writingmagnetic information on said disk, said magnetic head including: asubstrate base; a write head being fabricated above said substrate base,including: at least two magnetic poles; an electrical insulation layerbeing disposed between said magnetic poles such that no portion of saidelectrical insulation layer is disposed at an air bearing surface (ABS)of the magnetic head; a fill layer being disposed around said electricalinsulation layer such that portions of said fill layer are disposed atsaid ABS surface; an induction coil being disposed within saidelectrical insulation layer.
 22. A hard disk drive as described in claim21 wherein said electrical insulation layer is composed of a substanceselected from the group consisting of an organic polymer and SiO₂.
 23. Ahard disk drive as described in claim 21 wherein said electricalinduction coil is a single layer induction coil.
 24. A hard disk driveas described in claim 21 wherein said induction coil is a multiple layerinduction coil, and wherein each layer of said multiple layer isdisposed within a separate electrical insulation layer, and each saidelectrical insulation layer is disposed within a separate fill layer,and wherein no portion of either said electrical insulation layer isdisposed at said ABS surface, and wherein portions of each said filllayer are disposed at said ABS surface.
 25. A method for fabricating amagnetic head, comprising the steps of: fabricating a write head above asubstrate base, including the steps of: fabricating a first magneticpole; fabricating an electrical insulation layer above said firstmagnetic pole, such that no portion of said electrical insulation layeris disposed at an air bearing surface (ABS) of the magnetic head;fabricating a fill layer around said electrical insulation layer, suchthat portions of said fill layer are disposed at said ABS surface;fabricating an induction coil within said electrical insulation layer;fabricating a second magnetic pole above said induction coil.
 26. Amethod for fabricating a magnetic head as described in claim 25 whereinsaid electrical insulation layer is composed of a substance selectedfrom the group consisting of an organic polymer and SiO₂.
 27. A methodfor fabricating a magnetic head as described in claim 25 wherein saidinduction coil is a single layer induction coil.
 28. A method forfabricating a magnetic head as described in claim 25 wherein saidinduction coil is a multiple layer induction coil, and wherein eachlayer of said multiple layer coil is fabricated within a separateelectrical insulation layer, and each said electrical insulation layeris fabricated within a separate fill layer, and wherein no portion ofeither said electrical insulation layer is fabricated at said ABSsurface, and wherein portions of each said fill layer are fabricated atsaid ABS surface.
 29. A method for fabricating a magnetic head asdescribed in claim 26 wherein said fill layer is comprised of Al₂O₃. 30.A method for fabricating a magnetic head as described in claim 29wherein said etch stop layer is comprised of Al₂O₃
 31. A method forfabricating a magnetic head, comprising the steps of: fabricating afirst magnetic pole (P1) upon previously fabricated elements of themagnetic head; fabricating a P1 pole pedestal upon said P1 pole inmagnetic connection therewith; fabricating an etch stop layer upon saidP1 pole; fabricating an electrical insulation layer upon said etch stoplayer, said electrical insulation layer being patterned such that noportion of said electrical insulation layer is deposited at an airbearing surface (ABS) of the magnetic head; depositing a fill layer uponand around said insulation layer, portions of said fill layer beingdisposed at said ABS surface; fabricating an induction coil within saidelectrical insulation layer; fabricating a flat upper surface upon saidP1 pedestal and induction coil; fabricating a write gap layer upon saidflat surface; fabricating a P2 pole, upon said write gap layer.
 32. Amethod for fabricating a magnetic head as described in claim 31including the further steps of fabricating a patterned etching mask uponsaid electrical insulation layer, and conducting a reactive ion etchprocess to etch said induction coil trenches into said electricalinsulation layer.
 33. A method for fabricating a magnetic head asdescribed in claim 31 wherein said etch stop layer is comprised ofAl₂O₃, and said electrical insulation layer is comprised of a materialselected from the group consisting of an organic polymer and SiO_(2.)34. A method for fabricating a magnetic head as described in claim 31wherein said electrical insulation layer is comprised of an organicpolymer and including the further steps of removing said organic polymerfollowing said step of depositing said fill layer; and depositing anSiO₂ electrical insulation layer in place of said organic polymer; andfabricating said induction coil within said SiO₂ electrical insulationlayer.
 35. A method for fabricating a magnetic head as described inclaim 34 wherein said fill layer is comprised of Al₂O_(3.)
 36. A methodfor fabricating a magnetic head, comprising the steps of: fabricating aP1 pole layer upon previously fabricated elements of a magnetic head;fabricating a P1 pole pedestal upon said P1 pole in magnetic connectiontherewith; fabricating a first etch stop layer upon said P1 pole;fabricating a first electrical insulation layer upon said etch stoplayer, said first electrical insulation layer being patterned such thatno portion of said first electrical insulation layer is deposited at anair bearing surface (ABS) of the magnetic head; depositing a first filllayer upon and around said first insulation layer, portions of saidfirst fill layer being disposed at said ABS surface; fabricating a firstinduction coil layer within said first electrical insulation layer;fabricating a flat upper surface upon said P1 pedestal and firstinduction coil layer; fabricating a write gap layer upon said flatsurface; fabricating a second electrical insulation layer above saidwrite gap layer, said second electrical insulation layer being patternedsuch that no portion of said second electrical insulation layer isdeposited at an air bearing surface (ABS) of the magnetic head;depositing a second fill layer upon and around said second electricalinsulation layer, portions of said fill layer being disposed at said ABSsurface; fabricating a second induction coil layer within said secondelectrical insulation layer; fabricating a third electrical insulationlayer above said second induction coil layer; fabricating a P2 pole yokeabove said third electrical insulation layer.
 37. A method forfabricating a magnetic head as described in claim 36 including thefurther steps of fabricating a patterned etching mask upon each saidfirst and second electrical insulation layers, and conducting a reactiveion etch process to fabricate said first and second induction coillayers within said first and second electrical insulation layersrespectively.
 38. A method for fabricating a magnetic head as describedin claim 36 wherein said first and second etch stop layers are comprisedof a Al₂O₃; and wherein said first and second electrical insulationlayers are comprised of a material selected from the group consisting ofan organic polymer and SiO₂.
 39. A method for fabricating a magnetichead as described in claim 36 wherein said first and second electricalinsulation layers are comprised of an organic polymer, and including thefurther steps of: removing each said first and second organic polymerelectrical insulation layers following said step of depositing a filllayer; and depositing an SiO₂ electrical insulation layer in place ofeach said first and second organic polymer electrical insulation layers;and fabricating said first and second induction coils within said SiO₂electrical insulation layers.
 40. A method for fabricating a magnetichead as described in claim 39 wherein said first and second fill layersare comprised of Al₂O_(3.)